(a) Field of the Invention
The present invention relates to a strength training control device using a motor assembled beam-type load cell, and more particularly to a servo device that uses an beam-type load cell for feeding back a load value and a servo controller and comparing the load value with a set value and adjusting the load value to drive a motor, such that the exercise load can be equal to the set torque value.
(b) Description of the Related Art
In addition to a base frame and a link mechanism, exercise equipments or fitness machines for strength training generally come with a resistance device for providing an exercise load. With reference to FIGS. 1 and 2 for perspective views of a stretch trainer as disclosed in U.S. Pat. No. 7,396,319, the fitness machine of this sort comprises: a stretching part 12 disposed at the front of a seat 11 and provided for pressing a user's thighs 121 and calves 122 together; a movable inward/outward direction switch part 13 disposed at the bottom of the fitness machine, and a resistance arrangement 14 disposed on a lateral side of the fitness for providing a resistance to the load, and linked with the movable inward/outward direction switch part 13 by a cable 15. If a user's thighs and calves drive the stretching part 12 towards the interior or exterior to link the movable inward/outward direction switch part 13, then the resistance arrangement 14 will provide the exercise load to the user.
In general, the conventional resistance arrangement 14 is composed of a plurality of weights 141 stacked on top of one another and used as the exercise load, but the conventional way of providing a load has the following drawbacks:
1. The weights 141 usually come with a large volume and occupy much space, and users have to add or remove the weights 141 to adjust the exercise load, not only wasting time and efforts, but also failing to continue the exercise while making the adjustment. As a result, it is difficult to achieve the expected exercise effect.
2. The load including the weights 141 is heavy and difficult to make adjustment, and users cannot have a continuous and smooth variable load according to a set curve, and thus causing an ineffective exercise effect and incurring a potential risk of muscle injuries.
3. When the load including the weights 141 is lifted to ascend and released to descend by a transmission cable 15, a very loud sound will be produced, not only distributing others, but also irritating the exerciser. Furthermore, the transmission cable 15 must be operated with components such as a winch pulley, and thus the structure of the fitness machine becomes more complicated.
The load device of the conventional fitness machine 10 has the aforementioned drawbacks and obviously requires improvements.
Some of the conventional exercise equipments or fitness machines adopt the motor torque as a resistance control of the exercise load, and an optical chopper is linked to the motor shaft, and an optical coupler is installed at its periphery to constitute an exercise stroke sensor used for controlling the electric current of a motor and used as a curve load to achieve a purpose of successful fitness. However, the optoelectronic mechanism has a relatively large volume and takes much installation space, and it also has the disadvantages of a relatively low precision, a relatively poor durability and a relatively high manufacturing cost, so that the optoelectronic mechanism cannot be used extensively by users.